Cooling systems for internal combustion engines, such as those powering locomotives, are known in the art for the purpose of maintaining engine temperature and lubricating oil temperatures within desired operating parameters. In addition, the cooling system is used to reduce the temperature of the charge air. In typical cooling systems, ambient air is forced through heat exchangers and the cooling capability is constrained by the temperature of the ambient air as well as other factors. There are two common types of cooling systems commonly found in locomotives.
For example, the first type of cooling system consists of a Y-shaped pipe on the engine which splits the coolant flow into two radiators. The coolant exits both the radiators and enters an oil cooler, which is in parallel to an expansion tank. From the oil cooler the coolant is combined with the outlet of the expansion tank and then it enters a pair of pumps that are mounted on the engine block. The pumps then circulate the coolant through fluid passages within the engine. Some of the fluid flows through passages in the cylinder liners and heads while the remainder exits the engine at the opposite end of the pumps and enters a pair of intercoolers that are located on each side of the engine. After the coolant absorbs the heat from the intercooler, it then re-enters the engine via another fluid passage and combines with the fluid coming from the cylinder liners and heads. The coolant then exits the engine and is diverted through the Y-shaped pipe to the radiators restarting the cooling process.
The above prior art cooling system allows the engine cylinder liners, cylinder heads, oil cooler and the intercoolers and crankcase exhaust elbows that are located in the upper deck of the crankcase to be maintained at acceptable temperature levels. The coolant temperature is at its lowest as it is coming out of the radiators, and this coolant is provided to the oil cooler. As the coolant continues through the system and flows through the engine and intercoolers, it may warm up considerably and not lose heat until it once again passes through the radiators. In this typical prior art cooling system, the engine coolant enters the engine around 180 degrees Fahrenheit and exits the engine around 190 degrees Fahrenheit.
The second type of prior art cooling system is similar to the first type with the exception that the coolant flows out of the engine through a water discharge header and is combined with coolant that exits from the intercooler and turbocharger. The coolant then enters a control valve that will either direct the coolant to the radiator or expansion tank depending upon the temperature of the coolant. If the coolant is warm, it will be directed to the radiators and then to the expansion tank. The coolant then passes through the oil cooler to a pump which circulates the coolant through the water inlet header into the engine turbocharger and intercoolers. If the coolant temperature is cold, which is typical during engine start up, the control valve shall route the coolant such that it bypasses the radiators, and flows directly into the expansion tank, and continues the process as described above. This type of cooling system is designed to maintain a coolant temperature between 182 degrees Fahrenheit and 200 degrees Fahrenheit.
These traditional cooling systems of the prior art have a disadvantage because these systems do not allow the flexibility to provide a lower coolant temperature to the intercoolers. The lowest coolant temperature that is received by the intercoolers of both systems is dictated by the coolant temperature that is required by the cylinder liners and cylinder head.
The disclosed split cooling system and method is directed to overcoming one or more of the disadvantages listed above.